/*
 * Copyright (c) 2004-2005 The Regents of The University of Michigan
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Authors: Gou Pengfei
 *
 * Date:    Mar. 2011
 */

#ifndef __CPU_EDGE_BTB_HH__
#define __CPU_EDGE_BTB_HH__

#include <vector>

#include "base/types.hh"
#include "config/the_isa.hh"
#include "arch/isa_traits.hh"
#include "cpu/edge/pred/base_predictor.hh"

/**
 * Indirect btb used by Type-Only Next-Block predictors
 * */
template<class Impl>
class BTB : public BasePredictor<Impl>
{
  private:

    enum TableMode
    {
        UnknownTableMode,
        NormalTable,
        AliasFree
    };

    struct BTBEntry
    {
        BTBEntry(BasePredictor<Impl> *ptr) : 
            target(0x0),
            hysteresis(false),
            valid(false)
        {}

        Addr target;
        bool hysteresis;
        bool valid;
    };

  public:

    enum IndexType
    {
        ExitHistory = 0,
        TypeHistory,
        BinaryHistory,
        PathHistory,
        PredicationHistory,
        NoHistory,
        UnknownIndexType
    };

    BTB(DerivEdgeCPUParams *params);

    ~BTB();

    void reset();

    Addr lookup(const Addr &PC, std::vector<uint64_t> & hist);

    void update(const Addr &PC, std::vector<uint64_t> & hist, Addr correct_target);

    /** Currently counter bits of BTB is sticked to 1. */
    int getCounterBits() { return 1; }

  private:    

    uint64_t calcIndex(const Addr &PC, std::vector<uint64_t> & hist);

    PredictorTable<BTBEntry, Impl> btb;

    uint64_t numEntries;

    uint64_t idxLength;

    uint64_t idxMask;

    uint64_t blockShiftAmt;     

    uint64_t historyLength;

    uint64_t historyMask;

    IndexType indexType;

    TableMode tableMode;
};

#endif // __CPU_EDGE_BTB_HH__

